Fiber Optics Illustrated Dictionary - Part 89 ppt

Fiber Optics Illustrated Dictionary A sniffer is a useful system administration tool for monitoring and logging peak traffic times, network load, and possible problems. This information can help an administrator tune a system to operate effi- ciently. See packet sniffer, Sniffer. 5. A radio direc- tion-finding tool for locating radio transmitters. See Ultra sniffer. 6. A detective or investigative journal- ist who sniffs out (investigates) information as desired by clients or editors. Sniffer A registered trademark of Network General Corporation. The term "sniffer" has been used for de- cades in the search and rescue and law enforcement communities to refer to working dogs that are trained to sniff out fugitives, lost individuals, or chemical substances. The term has also historically been used in the radio community to refer to receiving devices that locate the source of radio signals. These direc- tion finders help to trace signals emanating from sources such as wildlife radio collars or radio listen- ing devices (bugs). With the advent ofcomputer sniff- ers, Network General Corporation has trademarked the term in the context ofsoftware utilities and network analyzers and the firm endeavors to protect this registered trademark. See Sniffer Network Analyzer. Sniffer NetworkAnalyzerA commercial product for analyzing local area network (LAN) traffic, first in- troduced in 1988 by Network General Corporation. The software provides a log of traffic, a suite of alarms, and various statistics. The corporation spe- cializes in fault and performance management solutions for enterprise networks. Sniffer Technologies Acommercial vendor ofwire- less monitors and network traffic analyzers and re- porting products, including Sniffer Distributed, Sniffer Wireless, Sniffer Optical, and others. sniffingjargon In computer networks, the process of looking at network data for testing, diagnosis, or unauthorized purposes. Because the Internet as awhole is a shared system, rather than a switched system (though switched portions exist), it is relatively easy to breach asystem with software and hardware tools provided for network testing and administration. One type of scouting sniffer for clandestine use captures the first fe~ hundred bytes of every remote session or file download/upload, so that the unauthorized snoop can scan the sessions for interesting information that might suggest a closer look. Snitzer, Elias (ca. 1922-) An electrical engineer and professor emeritus at Rutgers University, Snitzer demonstrated with Hicks that tiny-diameter fiber cores could be used to transmi t light as asingle mode wavelength. He authored articles on dielectric waveguide modes in the Journal of the Optical Soci- ety of America, in 1961 and coauthored "Amplifica- tion in a Fiber Laser" in Applied Optics, in 1964. In 1990, he coauthored articles on rare earth doping of optical fibers. Snitzer was elected to the National Academy of En- gineering in 1979 and worked for many prominent finns in optical technologies, including Polaroid Cor- poration, American Optical Corporation, and Honey- well. In 1995, he became president ofPhoto Refrac- 872 tive Enterprises, Inc. Snitzer is responsible for many firsts in the field of optical waveguides and development of glass, erbium, and ruby lasers. See Kao, Charles K. SNMP See Simple Network Management Protocol. SNOM See scanning near-field optical microscopy. snoop A testing and maintenance software tool for Solaris that enables the user to capture and inspect each packet in packet-based network traffic. It uses both the network packet filter and streams buffer modules for packet capture and displays them as received or logs them to a file. It is similar to tcpdump and related to etherfind (SunOS). The snoop utility can be used to tune network variables, to detect re- transmissions, duplicate acknowledgments, and other aspects of the network configuration. snooper, snooperscope, night scope A device designed to enhance night vision by sending out and intercepting an infrared beam. The incoming beam is interpreted into an image that shows objects not visible to the human eye. snow An undesired aberration in a broadcast or display ofa video image in which there are many ran- domly distributed speckles, often white. Snow can result from transmission problems, such as a weak or drifting signal, or from display device problems, as in a cathode-ray tube (CRT). SNVT (pran. snivit) See standard network variable type. SOA See semiconductor optical amplifier. Societe Internationale de Telecommunications Aeronautiques SITA. An international airline reser- vations and telegraphic transmissions service back- bone network established in 1983. Society for the History ofTechnology SHOT. An interdisciplinary organization dedicated to fostering and promoting an interest in the development of technology and how it affects society and culture, and to promoting scholarly study ofrelated documents and artifacts. Members include individuals, professionals, museums, scientists, and librarians. The organization was formed in 1958 and is headquartered in the Department of History of Science, Medicine, and Technology at Johns Hopkins University. Society ofBroadcast Engineers, Inc. SBE. Anon- profit organization providing publications, workshops, a certification program, and liaison with important regulatory agencies such as the Federal Com- munications Commission (FCC) in order to promote education, standards, and professional competency in the broadcast engineering industry. The SBE was founded in 1963 and has since grown to over 100 chapters in the U.S. and abroad. It publishes the quar- terly journal The SBE SIGNAL. http://www.sbe.org/ Society of Cable Telecommunications Engineers Inc. SCTE. A U.S. national nonprofit professional organization founded in 1969. The society includes over 13,000 members from around the world, representing a broad spectrum ofcable professionals. The society provides education, certification, and standards development. http://www.scte.org/ Society of Motion Picture and Television Engi- neers SMPTE. An international organization © 2003 by CRC Press LLC originally founded in 1916 as the Society of Motion Picture Engineers. The T was added in 1950 to en- compass the emergence of the television industry. The society includes over 8500 members in 72 countries, including engineers, technical directors, and production/post-production professionals dedicated to advancing the theory and application of motion-picture technologies. SMPTE contributes to standards development, encourages consensus-based recommended practices (RPs), and industry engineering guidelines (EGs). In 1957, the society was awarded an Oscar for its contributions to the advancement of the motion picture industry. It has also received three Emmy awards for various recording and video systems and standards. SMPTE is best known for developing SMPTE time code methods, which are used for video editing. When video tape began to be widely used for recording and editing, a way was needed to synchronize edits, to locate specific places on the tape, and to dub sound to match the video sequences. SMPTE began in 1969 to develop a standard for digitally encoding time information in terms of hours, minutes, seconds, and frames onto audio or video tape. See MIDI time code, SMPTE time code. http://www.smpte.org/ socket 1. A means of providing unique identification to which or from which information is transmitted on a network. RFC 147 specifies a socket as a 32-bit number; even sockets identify receiving sockets, odd sockets identify sending sockets. Each socket is iden- tified with a process running at a known host. SOCKSAn access and security technology designed to provide a framework for TCP and UDP client! server applications to conveniently, transparently, and securely utilize and traverse a network firewall. There have been a number of versions of SOCKS, with RFC 1928 representing version 5. Version 5 adds UDP and authentication capabilities, and extends ad- dressing to accommodate the future needs ofIPv6. The protocol fits between the application layer and the transport layer and does not provide ICMP message- forwarding services. Traversing a firewall securely depends upon the various authentication and encapsulation methods selected and used in the ne- gotiation between the SOCKS client and server. See firewall, gateway, proxy, RFC 1928. sodium vapor lamp A lamp that glows a warm golden color, from the passage ofelectricity through metallic vapors in acylinder encased in a glass tube. Sodium vapor lamps have been used as street and bridge lamps. See mercury vapor lamp. soft copyA stored image, document, or file which is recorded on a medium which must be accessed with some type of technology in order to be viewed, ma- nipulated, or displayed. Soft copies commonly exist on hard drives, floppy diskettes, tapes, CDs, and other magnetic or optical media. soft transferA term for an electronic monetary trans- action which precedes the actual exchange of funds between individuals or banking institutions. A paper check is a type of soft transfer. It is a monetary trans- action which is not finalized until the money is with- drawn from the bank. Similarly, online, many monetary transactions which are soft transferred and later "hard transferred" from the actual bank or other fi- nancial institution, such as a credit union. SoftCardAn early commercial product from Micro- soft, from an idea suggested by cofounder Paul Allen. The SoftCard was an internal peripheral card equipped with a Z80 processor, which ran CP/M-80 from Digital Research. This card, when installed in an Apple II computer, allowed its user to install and run CP/M-compatible applications programs. SoftSource Corporation/Catarra A Colorado and Bellingham-based firm that has developed a next- generation wireless mobile Personal Digital Assistant (PDA) macrobrowser that works transparently with the World Wide Web. This product may define the future of mobile wireless Web browsing. Recogniz- ing the improved capabilities of newer PDA devices, the developers, Scott Sherman, Mike McMullen, Dan Suslo, and Steve Work, created an applica~ion engine and server technology compatible with HTML, that is not dependent upon specialized subsets (e.g., Wire- less Application Protocol) or PDA languages characteristic of other microbrowsers. See PDA macrobrowser for an illustration. See PDA microbrowser, Wireless Application Protocol. software Computer instructions stored on a medium which is reasonably portable and accessible by users. Actually, the distinction between hardware and software is much less clear than many people real- ize. It may seem reasonable to designate everything inside the computer as hardware and everything that holds information that can be inserted into external storage read/write devices as software, but that's not really the best distinction. Floppy disks and computer chips are tightly integrated hardware/software com- binations whether external or internal, so the matter is really one ofaccessibility coupled with structure. Since computer instructions stored on disks are easily read, written, and moved, they are thought of as software. Since computer instructions on computer chips are not easily read or written and not easy for a lay person to access or move, they are considered part of the hardware. The lowest level software functions are programmed into the computer chips themselves. At the hardware operations level, this software acts to start up the system, test it, bootstrap the device drivers to come online, and initiate the operating system to accept user input and output, and to otherwise communicate with the central processor. Some of these operating instructions may be read, in tum, from hard drives, CD- ROMs, cartridges, or other storage media. High level software interacts with the user through application programs. Software is created with a variety of programming, editing, debugging, compiling, interpreting, and link- ing tools in a great assortment of languages, which are general purpose or optimized for specific types of programming. See programming. Software & Information Industry Association SIIA. A trade organization representing companies 873 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary that create, distribute, and facilitate the use of information in print and digital formats. Evolved from an organization originally founded in 1968, SIIA was established through a merger of the Software Pub- lishers Association and the Information Industry As- sociation, in 1999. SIIA promotes the information industry, represents its members in government policy and regulatory affairs, and provides a business development support network for top executives in the field. SIIA is based in Washington, D.C. http://www.siia.net/ Software Engineering Research Network SERN. An engineering and research joint venture of the De- partment of Computer Science and the Department ofElectrical and Computer Engineering at the Uni- versity of Calgary, Alberta. It is sponsored by the government of Alberta, University of Calgary, Mo- torola, Computing Devices, and Northern Telecom. Software PublishersAssociation SPA. See Software & Information Industry Association. solar cell In the 1940s, Bell Telephone Laboratories developed a storage cell from thin strips of silicon which had the characteristic of developing a charge in the presence of light. Since the silicon is not directly depleted in this process, solar cells are not sub- ject to the limited life spans oftraditional wet and dry cells. Solar cells have since been developed and refined in many ways and are used in many aspects ofelectronics. See photovoltaic. Solaris Apopular 32-bit operating system from Sun Microsystems that is commercially distributed, as is their SunOS operating system and, more recently, OpenStep. Solaris is multiprocessing, multithreaded, and network-friendly (using NFS), based on an open systems architecture. Many large Internet Services Providers, university systems, and enterprise local area networks (LAN s) run on Solaris. Solaris is available for various Sun SPARC, Intel-based, and Motorola-based systems. solenoid A long, cylindrical, current-carrying coil with properties similar to a bar magnet, into which an iron bar will be drawn when current is applied to the coil. Solenoids are commonly used in circuit breakers which have replaced traditional fuses. See electromagnet. Siimmering, Samuel Thomas von (1755-1830) A Prussian anatomist and inventor, Sommering was one of the earliest inventors oftelegraphic technology. Based on the work ofF. Salva, he developed an elec- trochemical wire telegraph which signaled letters and numbers through the application ofcurrent from a voltaic pile to a specific wire such that it created bubbles in an acid bath at the receiving end. Each wire corresponded to a character, with the wires and frame at each end looking very much like a threaded loom. This invention, which was demonstrated to the ANSII Standards Related to SONET- Examples ANSI Standard Title Subtitle T1.105.01-l995 Synchronous Optical Network T1.105.02-1995 Synchronous Optical Network T1.105.03-1995 Synchronous Optical Network T1.105.03a-1995 Synchronous Optical Network Tl.105.04-1995 Synchronous Optical Network T1.105-1995 T1.105.05-1994 Tl.105.06-1996 T1.l05.07-1996 T1.l05.09-l996 T 1.119-1994 T1.119.01-1995 Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Basic Description including Multiplex Structure, Rates, and Formats Automatic Protection Payload Mappings Jitter at Network Interfaces Jitter at Network Interfaces - DS 1Jitter Data Communication Channel Protocol and Architectures Tandem Connection Maintenance Physical Layer Specifications Sub-STS-1 Interface Rates and Formats Network Element Timing and Synchronization Operations, Administration, Maintenance, and Provisioning - Communications OAM&P Communications Protection Switching Fragment SONET Multiplexing Techniques 874 Technique Interleaving Single-stage interleaving Two-stage interleaving Type of interleaving Interlaces individual bytes Direct byte interleaving Direct byte interleaving Notes Reduces overhead at receiving end STS-N signal created directly Accommodates European lTV -T rate © 2003 by CRC Press LLC SONET multiplexing SONET signals can be multiplexed to make efficient use of network capacity. U.S. Europe Bit rate STS-l 51.84 Mbps STS-3 STM-l 155.52 Mbps STS-12 STM-4 622.08 Mbps STS-24 STM-8 1244.16 Mbps STS-48 STM-16 2488.32 Mbps STS-192 STM-64 9953.28 Mbps signals to form a multiplexed, switched signal that can be transported together. This is done to accommodate broadband services such as ISDN. Following is an overview of some of the bit rate speeds for the Synchronous Transport Signal levels and how they compare to European equivalents. This chart only indicates bit rates; the frame formatting for each system differs even further. SONET InteroperabilityForum SIF. An organization devoted to identifying and suggesting solutions to SONET interoperability issues, founded in 1994. Various workgroups work on topics such as remote login implementations and user requirements, interoperability with specific systems (e.g., TARP), architecture requirements, information models, access protocols and more. The SIF findings and recommendations are published as SIF Approved Documents. Here is a small selec- tion to give an idea of the scope of the documents. Most are available online; some can be obtained in paper format upon request. Focus TitleNumber SIP -007 -1996 Graphical User Interface Design Principles for the Development of OAM Graphical User Interfaces SIP -009-1197 Remote Login NE-NE Remote Login Implementation Requirements Specification SIP -020-1998 Testing IS to IS Abstract Test Suite SIP -023-1998 Infonnation Modeling Network View Model for Connection Management and Fault Management NSIF -03 1-1999 Architecture Architectures for an IP-Based DCN NSIP-038-2000 Security NSIFRequirements for a Centralized Security Server Academy of Science in Germany in 1809, predated Wheatstone and Morse technologies by three de- cades. Sommering improved upon Salva's design by extending the transmission range of the device and later collaborated with Schilling, who made some sig- nificant contributions to early electromagnetic teleg- raphy. See Salva i Campillo, Francesc; Schilling, Pavel; Steinheil, Karl August. sonar Sonar is currently considered to be the acro- nym for sound navigation and ranging (other phrases have been suggested). It is essentially a technology for generating and directing sound signals with the intent of analyzing the returning echoes to determine information about the size, shape, and relative distance of any objects encountered by the outgoing sound waves. Sound requires a medium in which to travel. It is, in fact, a disturbance of a medium and, thus, sonar is used for probing elastic media such as water and, to a lesser extent, air (as in robotics). SONET Synchronous Optical Network. SONET is a set of ANSI telecommunications standards which specify a modular family of rates and formats for synchronous optical networks. SONET provides a standard operating environment for managing high bandwidth services, and incorpo- rates multiplexing, service mappings, and standard- ized interfaces, so commercial vendors can develop interconnecting technologies. SONET has been adopted by the ITU-T as the basis for the Synchronous Digital Hierarchy (SDH) transport system, and is a subset of this system. SONET is based on STS-l which is suitable for T3, and SDH is based on STM-l, suitable for E4 transmissions. Communication between nodes, to permit control, provisioning, administration, and security, is accomplished through the Synchronous Transport Signal (STS) transmitting at a line rate of 51.84 Mbps. The STS comprises payload information and signaling and protocol overhead. Since the two ends of a SONET transmission may vary in format and speed, data are converted to the STS format, transmitted, and, when received, converted into the appropriate user format. OAM&P is integrated into SONET. See detailed information in the following listings. SONET ANSI standards A number of important American National Standards of Committee TI related to SONET are available from ANSI and described in the form of abstracts on the Web. See ANSI Standards Related to SONET chart. SONET frame The frame length is 8000 fps or 125 flsec. SONET uses Synchronous Transport Signal level 1(STS-l) as its basic signal rate of51.84 Mbps. SONET frames are organized in a row by column structure totaling 810 bytes. Transport overhead is contained in the first three columns and is subdivided to include section and line overhead. The remaining columns, from four to 90, are used for the Synchro- nous Payload Envelope (SPE). The STS-N frame consists of frame-aligned, byte- interleaved N STS-l signals. The STS-Nc frame consists ofconcatenated STS-l 875 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Class A Payload independentfunctions Required by all payload types Class B Mapping dependentfunctions Required by some payload types Class C Application-specificfunctions Class D Reservedforfuture use There are a number of ways to accomplish this, as shown in the SONET Multiplexing Techniques chart. SONET optical interface layers SONET includes a hierarchy of interface layers. Each one builds on the previous; from high to low, they are path layer, Line layer, section layer, and photonic layer. Individual layers communicate to peers on the same layer and to adjacent layers above and below. SONET path overhead In SONET, path overhead is transported with the payload until the signal is demultiplexed at the receiving end. The path overhead supports four classes: SONET path terminating element PTE. The PTE is an element which multiplexes and demultiplexes the Synchronous Transport Signal (STS) payload and processes the path overhead as needed to originate or access it. If necessary, the PTE can also modify or terminate it. See SONET, Synchronous Transport Signal. SONET timing In SONET networking, synchronization is accomplished by referencing a high accuracy clock and information from its slaves, so synchronization characters between equipment nodes are not used. Due to the high data rates carried by SONET, it is important to maintain clock accuracy. The three major timing modes supported are external timing based on aclock, generated free run/hold- over timing from an internal clock, and OC-N signal line timing. SOP standard operating procedure. Sorokin, Peter P. (1931- ) An American physicist who worked in collaboration with Mirek [Cevcik] Class Functions Notes Stevenson, Sorokin developed the first uranium laser, in 1960, that would set the stage for future tunable continuous wave lasers. At about the same time, Schmidt et al. were developing similar technology in Germany. Sorokin continued to work with laser technology, developing a dye laser, demonstrated in 1966 at the IBM Laboratories with John Lankard. Dye lasers set the stage for tunable lasers. In 1991, Sorokin was awarded the Arthur L. Schawlow Prize in laser science. See laser history. sound Radiant mechanical energy produced by vi- bration, which requires a physical medium for its transmission (such as air), and is detected by hearing, accomplished through physical sound-detection, perception, and interpretation by the nervous system. Compared to light and heat, sound waves move very slowly. Human sound perception through hearing covers a frequency range from about 20 Hz to about 20 kHz, although lower, and sometimes higher frequencies are felt, though not heard, through vibrations in the body. Other creatures perceive broader, nar- rower, or more specific frequencies, and sound is a ubiquitous means of species communication. Enough is known about the nature of sound waves to record, reproduce, and modify them, and to propagate them over great distances. Humans can project unampli- fied voice through the air for a few dozen or hundred yards, depending upon atmospheric conditions. Whale songs will resonate for thousands of miles through water, although whale communication distances have been drastically reduced by interference from industrial shipping noise. See acoustics, sonar. sound spectrograph An instrument for measuring the structure ofspeech and displaying it visually, developed in the early 1940s by Bell Laboratory re- searchers. This opened the door to more objective, quantitative measures of speech, information that is ofinterest not only to speech therapists, physicians, and educators, but also to developers of communications technologies. sounder Asound amplification device incorporated into a communications receiver, usually a telegraph receiver, to make the code clicks audible to a human operator. Sounders were invented when it was noticed SONET Interface Layers Layer Peer Notes Path Services and path overhead mapping Transport services between path terminating equipment (PTE). Mapping signals to line layer format. Conversion between STS and OC signals. Line SPE and line mapping Transport of path layer payload and overhead across physical medium. Synchronization and multiplexing. Section STS-N and section overhead mapping Transport of STS-N across physical medium. Photonic Optical conversion Transport of data across physical medium. 876 © 2003 by CRC Press LLC that telegraph operators had learned to interpret Morse code clicks and transcribe them manually faster than a paper tape could print the messages. A mainline sounder was an adaptation that allowed variable adjustments without a relay. See resonator. SP stream protocol. See byte-stream protocol. space division multiple access SDMA. One of two common optical multiplexing techniques which uti- lizes an angle diversity receiver, that is, multiple receiving elements receiving from different directional angles. See wavelength-division multiple access. space-charge field In electronics, an electric field created outside the physical surface of a conductor or semiconductor. space-to-mark transition, S-M transition In tele- graphy, the momentary change when the system re- verses polarity, or changes from an open to a closed circuit. At this point, a small amount of delay must be taken into consideration, which can be plotted on a timing wave. The reciprocal is the mark-to-space transition. SpacewayA commercial constellation of geostation- ary communications satellites from Hughes Commu- nications. Spaceway was formed from the merger of the Hughes Galaxy Satellite Services and the PanAmSat Corporation. Hughes Electronics is a sub- sidiary of General Motors Corporation. Spaceway is intended to be a global broadband communications system with service planned for 2003. spade lug, spade tip A small, flat, notched (some- what U-shaped) conductive connector attached to the end ofa conductive wire in order to easily secure it to an electrical terminal by sliding the end around the mounting screw and applying pressure via a bolt, or by soldering. Spade lugs are still common inside small residential phone wire junction boxes, but in large installations, punchdown blocks and modular components are more prevalent. See lug. spam slang A term widely used on the Internet to describe annoying, unsolicited, irrelevant, illegal, or worthless communications, usually in the form of email orpublicpostings.It.s generally said that the word originated as a tongue-in-cheek reference to a Hormel meat product called Spam, which is fre- quently pilloried and satirized in the media. Whether or not that is the case, the spam on the Internet, especially in the form ofunsolicited email bulk promo- tion of get-rich-quick schemes and sex site promo- tion has become a big problem due to the intrusive way in which the spammers violate the space and pri- vacy of recipients. Not as often acknowledged is the fact that spam causes substantial expense to ISPs, and general annoyance and expense to users who pay for email or extra storage space. spamming slang Posting or emailingirrelevant.annoying, illegal, or unsolicited opinions or promotional materials, sometimes through anonymous mailers or with false return email addresses. SPAN Switched Port Analyzer. A Cisco Systems network switch feature for extending the monitoring capabilities of existing network analyzers into a switched Ethernet environment. SPAN takes the traffic at one switched segment and mirrors it onto a pre- defined SPAN port. A network analyzer which is attached to the SPAN port can monitor traffic on other compatible switched ports. spanningtree algorithm STA. A standard technique described in IEEE 802.1 which is incorporated into bridges in computer networks. For example, in Fi- ber Distributed Data Interface networks, it is incorporated into bridges that connect the primary and sec- ondary rings. The spanning tree logic can prevent duplicate bridging and allows the backup ring hub to handle bridging if the primary ring hub fails. See Fi- ber Distributed Data Interface, Token-Ring. Spanning Tree Protocol STR. A protocol based on IEEE 802.1 d that provides resiliency through system and link redundancy that is especially suitable for virtual local area networks (VLANs). spark A brief: bright, heat discharge, often from electrical or friction sources. Sparks are generated by spark plugs to fire up an engine or by matches or light- ers to fire up combustible substances such as wood, cardboard, or lighter fluid. Unintentional sparks may be dangerous and may occur as a result of incorrect electrical connections (shorts, crossed wires), inad- equate insulation, or contact with unintended conductive substances such as water. spark coilA device incorporating an inductive magnetic core surrounded by helical windings of conductive materials used to generate a spark. The spark coil was typically used in conjunction with a condenser and vibrator (or interrupter) for telecommunications applications. Spark coils are still used to ignite internal combustion engines, but for many electronics applications, transfonners began to replace spark coils in the early 1900s. See armature, coil, dynamo, :~::;a~:1~~:U~I~:~~~~Ss.~~j~s::~~~;:~. affects the behavior of the spark. If the gap is too large, the spark may not jump the gap. SPARS code Society of Professional Audio Record- ing Studios. A three-letter code found in compact discs which indicates the analog or digital nature of a portion of the recording history. For example, ADD indicates that the original recording was analog, the mixing was digital, and the mastering stage was digital. See compact disc. Spartan A family ofsatellites designed for remote sensing. In 1997 an unsuccessful Spartan mission occurred when astronauts failed to tum on the satellite before releasing it into space. Initial efforts to re- trieve the satellite were unsuccessful and it was manually retrieved later. In 1998, all /2-ton Spartan satellite was successfully used for capturing images of the Sun's corona from space. Before the Spartan was retrieved by the crew of the Space Shuttle Discovery in November 1998, it had already beamed hundreds of images to ground controllers. One of the interesting aspects of the Spar- tan 207 multipurpose satellite was a 132-pound Inflatable Antenna Experiment (IAE) that was de- ployed aboard the Space Shuttle Endeavor STS-77 877 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary mission. The IAE, resembling a flat, stiff parachute when inflated, was developed by JPL and L'Garde, Inc. as part of NASA's In-Space Technology Experi- ment Program. Spartan Remote-Sensing Satellite The Spartan 201 satellite, one in aseries of remote- sensing meteorological satellites, as part of a pre- launch Crew Equipment Integration Test (CElT) in the Kennedy Space Center. (NASA image.] The Spartan 201 is held by the Space Shuttle Columbia's Remote Manipulator System (RMS), De- cember, 1997, over the Pacific Ocean. The RMS, designed in Canada, released the satellite into freeflight. [NASA images.] spat 1. A unit of solid angle comprising the space about the vertex of an angle, equal to a sphere or 41t steradians. See steradian. 2. A unit of distance historically used by astronomers to represent 10 12 meters (terameter), now rarely used. spatial light modulator SLM. A computer-controlled optical or opticaVelectrical component that controls a beam of light through spatial dimensions through an array of optical modulators and associated detectors. Spatial light modulation can drive 2D image displays as well as projecting 3D spatial images. The effect is more easily understood by envisioning 3D holo- graphic images and then imagining that the image is created in realtime with light rather than being holo- graphically recorded in a static medium. Spatial modulators can modulate laser or metal halide light beams to create 3D images based upon the human characteristic of persistence of vision and, in more 878 sophisticated systems, the basic motion concepts of frame animation. Commercial SLMs are fairly recent and there are still many variations and experimental systems evolving. In general, however, SLMs work by sending a near- infrared or visible light pulse through various gratings and lenses to modulate the light, with the output pulse proj ected into an imaging system. F erroelec- tric or nematic liquid crystals are often used as the retarding material with synthetic fused silica as the substrate. The phase of the lightwave may be modulated, with the intensity of the light kept constant, or the amplitude may be modulated, changing the beam intensity and the phase profile (which may be cor- rected with dual modulators connected in series, for example). Polarizing elements may be optional. There are various ways to image the light beam. It can drive a 2D display like a computer/television display or it can be projected to a rotating 20 screen. Persistence of vision makes the successive images appear as 3D objects since one image is still briefly visible while the next is formed. Imaging successive frames at high speed and presenting the frames at a speed that makes it appear to the viewer as if there is natural motion (about 24+ frames/sec) is also possible, as frame rates in the order of over 2000 frames/ sec (which could combine imaging frames and im- plied-motion frames as the image changes over a set of frames) can be achieved with this technology. Thus, many types of effects and images are possible and people can walk around the image and see it in three dimensions at the same time. Spatial modulation technology has great possibilities for medical imaging, chemical analysis, the modeling of neural networks, optical computing, beam steering, spectroscopy, flat panel displays, entertain- ment, education, and volumetric computer-aided design. SPEC See Standard Performance Evaluation Corpo- ration. Specialized Common Carrier decision A decision by the Federal Communications Commission (FCC) in 1971 to permit competition with AT&T in the provision of specialized voice and data services. Specialized Mobile Radio SMR. Awell-established analog, trunked two-way radio dispatch system fa- vored by commercially dispatched passenger and cargo fleets, public safety, and local services (e.g., taxi). SMR enables a group of radio communications users to share a common channel through a central station. Allocated frequencies are in the 800- and 900- MHz ranges. In North America, more than two million users sub- scribed to SMR services, a number that was gradually increasing until bandwidth bottlenecks began to impact the service. In response, the Federal Commu- nications Commission (FCC) made available addi- tional radio spectrum frequencies in the 900- MHz range, in the mid-1990s, and above 860-MHz·in 1997, thus opening the door for SMR services to compete with niche areas of the cellular market. With digital technology being adapted to SMR © 2003 by CRC Press LLC services, considerable changes took place. First, Motorola developed a system called the Motorola Integrated Radio System (MIRS) and, more recently, Enhanced Specialized Mobile Radio (ESMR) is catching on, which makes ESMR competitive in some areas with cellular services. While SMR spectrum is more limited than cellular, it can be used over a longer range. The upgrade to digital technology has greatly accel- erated the increase in ESMR users in North America and Europe due to the improved quality of the sound and greater variety of services offered. See Enhanced Specialized Mobile Radio. Specification and Design Language SDL. An ITD- I-defined language for the description and specification of the behavior of telecommunications systems. XDL is an extension of this language. spectral spreading See spread spectrum clocking. spectral transmission In a fiber optic cable, the ra- tio between the incoming light and the outgoing light at the other end ofa fiber cable link. As light propa- gates through the fiber filament, it is reflected towards the cladding and back into the conducting core and may also be reflected in certain ways by the endfaces (points of entry and exit), and dopants or gratings wi thin the fiber. Whenever there are obstacles or microbends, some of the light is absorbed or lost through the cladding (if there are excessive bends or fractures in the cladding). It may even be stopped entirely or reflect back- wards if the bend radius of the fiber exceeds the angle at which the light reflects in the desired general di- rection. Thus, depending upon the length of the cable, its components, the degree of bend, the wavelengths used, fiber impurities, fiber fluctuations in density, dopants (deliberate impurities), and grating factors, the outgoing light is typically less than the incoming light. Thus, incoming light versus outgoing light can be plotted with respect to wavelength for a cable with specified properties. This can be modeled with computer software or tested directly with measuring probes in installed or sample cables. spectrographAn instrument for spreading light into its spectral components. By studying the brightness of the spectrum at each wavelength, it is possible to study the composition and characteristics of substances through their light-emitting properties and patterns. This is widely used by astronomers studying our solar system. spectrometerAn instrument that detects and records the spectral components of light. The main element is a dispersing component for separating light rays into their component wavelengths. Other typical components include a collimator to align the incoming light (which may beam directly to the collimator or come through a fiber optic probe), a prismatic grating to direct and condition the light reflected by the dispersing element, various concentrating lenses, and an optical detector. Once detected, the signal is sent to a display or recording device (e.g., charge coupled device) ~nd may further be analyzed by a signal processor. Echelle spectrographs enable a larger amount of the detector area to be used by creating higher dis- persion over shorter wavelength ranges for each order. See echelle grating, interferometer. spectrometer, massAn instrument for detecting and recording the differences in mass-charge ratios of ionized molecules or atoms that occur when a substance is stimulated by an electromagnetic force. This enables molecular properties to be separated/distin- guished, which is useful for assessing the structural and chemical properties of substances. spectrophotometer A versatile optical sensing and measurement instrument used in a variety of applications from chemical analysis to high energy physics research. The instrument may be used for evalu- ating the existing qualities ofa substance as light energy passes through it, or may be used in conjunction with externally applied energy (e.g., radiation) to apply controlled influences to the sample under study. Thus, the spectrophotometer measures the characteristics ofa substance through its absorption of light or the amount of light passing through the substance as compared to reference information. A spectrophotometer includes a phototube or photomultiplier tube to convert photon energy into electrical energy so that the characteristics may be measured with electronic circuits and viewed with electric- based display components. When the light emitted from a sample is dispersed with a monochromator, the resulting spectral lines can be analyzed and the results compared or combined with information from the photomultiplier tube. When a monochromatic light source (e.g., laser light) strikes a substance and emits electromagnetic energy at a different frequency from the source energy, a phenomenon called Raman scattering occurs. This effect may be amplified with a photomultiplier tube so that the wavelength difference can be used to assess qualities of the sample. Fiber optics are increasingly being incorporated into spectrophotometric and radiometric devices. Re- flected or weak emissions may be detected with photomultiplier tubes and optical filters and the function ofa monochromator may be handled by optical fibers. F or general reference, the diameter of commercial side-on and smaller gauge head-on photomultiplier tubes ranges from about 10 to 38 mm, with effective areas of about 3 to 34 mm. Depending upon the type of tube and its intended use, spectral response is typically around 160 to 185 om or 300 om at the low end ranging up to about 650 om or 850 to 900 om at the high end. A few specialized near-infrared components have a spectral response between about 400 to 1200 nm. Larger gauge head-on tubes range from about 51 to 127 mm, with effective areas of about 46 to 460 mm. See diffraction, phototube. spectroscopyA technique used by scientists to study the composition and/or characteristics ofa substance based upon an analysis of its light-emitting properties. Spectroscopy is useful for chemical and crys- talline structure analysis. In electronics, spectroscopy enables semiconductor components to be tested and monitored. The property 879 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary of phot 0 reflectance can help determine electron mo- bility; by beaming laser light ofa specific frequency into the semiconductor and influencing the dielectric properties, the optical response in terms of the reflectance coefficient may be determined. In medicine, fiber optic probes may be used in conjunction with spectroscopes to assess the characteristics of healthy and diseased tissues to aid in medical diagnosis. In astronomy, spectroscopy has enabled more detailed study of stars, beyond distance and brightness. spectrum In general, a continuous sequence or range of some property or radiant energy. Many phenom- ena are described in terms of their characteristics or position within the spectrum of radiant energy, including electromagnetic, radio, sound, visible light, specific colors, etc. See band allocations, radio, sound, visible spectrum. speech recognition The process of receiving, interpreting, and parsing spoken words. On computers, this is often accomplished with a microphone input device, an analog-to-digital peripheral card, and a software program that works independently or in conjunction with other programs such as word processors. It may also include noise-canceling features that help to separate the voice of the speaker from ambi- ent room noise such as the hum ofcomputers or low conversations in the distance. Speech recognition is distinct from voice recognition in that voice recognition is the processing of the particular characteristics ofa specific voice so that it can be recognized, such as in a security identification system. Voice recognition does not involve making sense of the content of the message, as does speech recognition. Speech recognition systems typically require a minimum sampling rate of about 3000 samples per second in order to reliably recognize words. Many systems sample at 8000 samples/sec. Speech recognition can be used to dictate text, give commands, and receive information over a communications system in digital or altered form. Since speech recognition is a complex process, most current systems are specialized to recognize a specific limited vocabulary as spoken by anumber of speak- ers in a specified language or a general (or specific) vocabulary as spoken by one particular speaker. More sophisticated systems can recognize and react to sen- tences and grammatical structures. Many speech recognition programs have training algorithms (speaker adaptive algorithms) included so the software can gradually adapt to the idiosyncrasies ofa particular speaker's prounciation and mode ofexpression. In the mid-1990s, speech recognition computer software began to be reliable and inexpensive enough to interest small businesses and individual consumers, and its use will probably spread through a variety of applications, perhaps adding another means of input to standard software such as word processors and electronic mail programs. See phonemes, voice recognition. speech synthesis The reproduction of audible human communication, through the use of computers. There 880 are many different ways to create synthesized voice. Sound samples of human voices uttering certain words, sounds, and syllables can be recorded as separate entities, stored digitally, and then combined and played back to create words and phrases. Other schemes, such as pure digital recreation ofvoice-like sounds are also available, but tend to have adistinctly mechanical quality to them. The most famous synthesized voice in the world is probably that of Stephen Hawking, world acclaimed physicist who talks indirectly through words and phrases programmed into a computer keyboard installed on his wheelchair. When Mr. Hawking is fin- ished composing the message, it is played to the lis- tener through a speech synthesizer. Synthesized voices are used in multimedia applications, on storybook CD-ROMs, in automated tele- phonemail order and banking systems, etc. See pho- neme, speech recognition, voice recognition. Speech Technology and Research Laboratory STAR. Adivision of SRI International which engages in world-class research in speech technology using engineers, linguists, and computer scientists. Tech- nology developed in the STAR lab is fed to Nuance Communications for commercial development for telephony applications. Ofparticular interest to re- searchers is natural speech recognition (without the usual training to recognize a particular individual's voice) that can provide automated phone services or voice-based securities trading. Other areas of research include text-to-speech translation, visual information systems development, and digital encoding of audio signals. speed dialing A means of keying in a shorter code to represent a longer one in order to speed up the dialing oflong phone numbers. See abbreviated dialing. SPF I. shortest path first. 2. See stateful packet fil- tering. SPIDGS Simple PRIGS. See PHIGS. SPI I. Security Parameters Index. 2. Service Provider Interface. SPID See Service Profile Identifier. SPIE - The International Society for Optical En- gineering SPIE is a nonprofit, international professional society in Bellingham, Washington, dedicated to advancing research, engineering, and applications in optics, photonics, imaging, and electronics. SPIE produces educational publications, sponsors confer- ences and workshops, and now also provides Web re- sources in cooperation with the Institute of Physics (lOP). http://www.SPIE.org/ http://optics.org/ spilling In a fiber optic cable assembly, light that exceeds the critical angle within which total internal reflectance (TIR) is possible and thus passes through the cladding and is lost. Sometimes spilling is delib- erately induced (e.g., by bending the fiber) to produce light effects at periodic intervals along the length of a fiber. In general, however, it is undesirable, resulting in losses that occur in the power of the light signal as it reflects through the fiber link. See cladding. SPINS See Security Protocols for Sensor Networks. SPIRITS A network architecture that supports © 2003 by CRC Press LLC SPIRITS services originating in the Public Switched Telephone Network (PSTN) interacting with the In- ternet. In simple terms, it is an architecture to support popular telephone services over Internet phone connections, such as Internet-based Caller ill, Call Forwarding, etc. The SPIRITS architecture was sub- mitted as an Informational RFC by Slutsman et al. in June 2001. Implementation of SPIRITS services requires an In- ternet Protocol (IP) host installed with SPIRITS-sup- porting software and identification (e.g., PINs) for communicating with other SPIRITS servers. Once a host is SPIRITS-enabled, a user may connect to the Internet and register a service session and optionally specify the session duration. The SPIRITS architecture consists of a number of service control, service switching, client, server, and gateway functions as well as a number of interfaces. Interface Notes Interface A A conduit for PINT requests/re- sponses. Supports service session subscription, registration, and activa- tion ofa SPIRITS service. Interface B Notifies the subscriber of incoming calls and call infonnation and sub- mits asubscriber's choice of call dis- position to the SPIRITS gateway. Interface C Client/gateway communication. The gateway may, in turn, communicate with the SPIRITS server or may act as a virtual server, terminating requests without relaying them. Interface D SCF to client communication, sending parameters associated with the applicable IN triggers. The SCF translates user requests into corre- sponding actions. Interface E PINT to SCF requests. See PINT, RFC 2995, RFC 3136. splashing When using competitive operator services for long-distance calls, if the caller places a call from San Francisco to Portland and the alternate service is based in Los Angeles, the call is said to be splashed if the billing is determined by the distance from Los Angeles to Portland. See Operator Service Provider. splice lJ. 1. To unite or combine separate lines, usually by weaving together the individual strands. 2. In electrical splices, the joining ofconducting wires to complete or extend a circuit. Care is usually taken to match the data lines so as not to cross one type of data channel with another, and bare wires are generally covered with an insulator such as a cap, electrical tape, or plastic shrink sleeve to prevent short circuits or shock. 3. In fiber optics, ajoint where two ends of a fiber optic waveguide are mechanically joined or fused to facilitate the unimpeded travel of light across the splice joint. See fenule, fusion splice, splice guard. splice enclosureAcomponent for protecting spliced cable where extra protection or safety requirements are needed. For example, asplice enclosure for electrical wires may provide extra protection against moisture, rodent chews, or electrical interference, as well as protecting from shock hazards. For fiber optic cables, a splice enclosure can help align multiple cables and provide extra protection to splicedjoints so that the waveguide is not interrupted or compromised. Asplice enclosure is sometimes be called asplice organizer shelf or fiber organizer shelf and may be rack mountable. Asplice guard may be used in place of a splice enclosure in some circum- stances. See splice guard, splice tray. splice guard An extra support component for a fused or mechanical joint that fits over a sleeve. It is usually shorter than the sleeve, in case the sleeve provides color or printed code information. For fiber optic cables, a splice guard is usually secured without heat or glue and provides extra protection against external forces that might compromise ajoint, such as side or axial pull. Asplice guard is usually applied and secured with a specialized crimp tool. A splice guard is sometimes used instead ofa splice enclosure in situations where only a few fibers need protection or where space is limited. Commercial products usually meet relevant Bellcore GR-326- CORE specifications (humidity, dust, and thermal aging, etc.). See splice enclosure. splice tray A tray for protecting spliced cables, especially for temporary storage prior to installation. When the tray is used to organize multiple spliced cables for longer periods of time, ahardening gel may be used to support and secure the cables. See splice enclosure. splittingA ubiquitous function in computing in which ~~~~::~~;;;~~~;:~~:~~~~~~l~i. Splitting is usually used in a context where the data will be reassembled or rejoined when it reaches its intended destination or is needed by some application. See joining for a detailed explanation. SPNE signal processing network equipment. spoofing 1. Deceiving, covering up the identity of, impersonating, or otherwise conveying an impression ofbeing something else. 2. A means of gaining unauthorized access to a premises or system by deceit, impersonation, or other misrepresentation. spoofing, facsimile Facsimile devices, especially the desktop models, have not traditionally been speedy machines and many are designed to time out if no data is received for a while (in order not to tie up phone lines). With the advent of faxing over faster packet- based network connections, facsimile delays can lead to time-out problems in the connection that would interfere with the function of the fax machine. Spoof- ing extends the tolerance for these delays so that the fax can finish with the machine disconnecting. By padding and other methods, delays and packet 'jitter" can be smoothed over to spoofa realtime voice- line connection. A number of vendors have access server technologies that take into account the needs 881 © 2003 by CRC Press LLC . multiplexing SONET signals can be multiplexed to make efficient use of network capacity. U.S. Europe Bit rate STS-l 51.84 Mbps STS-3 STM-l 155.52 Mbps STS-12 STM-4 622.08 Mbps STS-24 STM-8 1244.16 Mbps STS-48 STM-16 2488.32 Mbps STS-192 STM-64 9953.28 Mbps signals to form a multiplexed, switched signal that can be transported together. This is done to accommodate broadband services such as ISDN. Following is an overview of some of the bit. Transport Signal level 1(STS-l) as its basic signal rate of51.84 Mbps. SONET frames are organized in a row by column structure totaling 810 bytes. Transport overhead is contained in the first three columns and is subdivided to include section and line overhead. The remaining columns, from four to 90, are used for the Synchro- nous Payload Envelope (SPE). The STS-N frame consists of frame-aligned, byte- interleaved N STS-l signals. The STS-Nc frame consists ofconcatenated STS-l 875 © 2003 by CRC Press LLC Fiber Optics Illustrated Dictionary Class A. Subtitle T1.105.01-l995 Synchronous Optical Network T1.105.0 2-1 995 Synchronous Optical Network T1.105.0 3-1 995 Synchronous Optical Network T1.105.03a-1995 Synchronous Optical Network Tl.105.0 4-1 995 Synchronous Optical Network T1.10 5-1 995 T1.105.0 5-1 994 Tl.105.0 6-1 996 T1.l05.0 7-1 996 T1.l05.09-l996 T 1.11 9-1 994 T1.119.0 1-1 995 Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Synchronous Optical Network Basic Description including Multiplex Structure, Rates, and Formats Automatic Protection Payload Mappings Jitter at Network Interfaces Jitter at Network Interfaces - DS 1Jitter Data Communication Channel Protocol and Architectures Tandem Connection Maintenance Physical Layer Specifications Sub-STS-1 Interface Rates and Formats Network Element Timing and Synchronization Operations, Administration, Maintenance, and Provisioning - Communications OAM&P Communications Protection Switching Fragment SONET

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